The present invention relates in general to active bolsters for occupant crash protection in automotive vehicles, and, more specifically, to a pleated expansion wall with transverse ribs that are bridged between adjacent pleats to fine-tune the deployment trajectory (i.e., shape or timing) of the deployed bolster.
An active bolster is a type of vehicle occupant protection device having a gas-inflatable bladder to absorb impacts and reduce trauma to occupants during a crash. As opposed to deploying air bag cushions through various openings, active bolsters use the interior trim surface itself to expand at the beginning of a crash event for absorbing the impact and dissipating energy through the action of an inflation gas. Co-pending application publication US2011/0316300A1, filed Jun. 26, 2010, entitled “Active Knee Bolster for Automotive Vehicle,” which is incorporated herein by reference in its entirety, discloses an active knee bolster integrated into a glove box door that is light weight and visually attractive. Active bolsters are also commonly integrated into door panels for side impact protection.
In a typical structure, an active bolster includes a bladder comprised of a front wall or panel that faces a vehicle occupant attached to a back wall or panel along a sealed periphery. One or both of the walls are deformable in order to provide an inflatable (i.e., expandable) bladder. The walls are initially spaced apart by a small distance while in their non-inflated condition. This allows ingress of the inflation gas in a manner that achieves an even inflation across the panel.
The front and back walls of a typical active bolster are comprised of molded thermoplastics such as polyethylene, polyolefin, or PVC. They can be blow molded or injection molded. The back wall commonly employs a pleated structure that unfolds in an accordion-like fashion during inflation to provide the increasing volume of the bladder for forming an impact cushion. So that the bolster follows an outward trajectory away from its rigid mounting structure and toward the passenger, the pleats may be placed circumferentially around the back bladder wall.
Circumferential pleats have typically resulted in an expansion trajectory that is perpendicular to the Class A surface in a generally symmetrical manner. This expansion profile has been desirable in most situations where the potential passenger interaction is symmetrical across the face of the bolster. In some situations, however, the Class A surface may be skewed with respect to the impacting passenger. For example, an instrument panel or dashboard in front of a front passenger seat may be curved or sculpted so that a glove box door is closer to the passenger on the left side than on the right side. A symmetric expansion of an active bolster in the glove box door would result in an uneven impact of the passenger with the bolster. An unsymmetric deployment trajectory can be obtained by shaping the pleats variably around the circumference as disclosed in pending U.S. application Ser. No. 13/460,869, filed May 1, 2012, entitled “Active Bolster with Unsymmetric Pleated Inflation.”
In the mass production of automotive vehicles, it is often desirable to utilize a component part without modification on many different vehicle models in order to obtain efficiencies of scale. However, mid-year improvements, model-year changes, and new vehicle applications may require certain changes to an existing design of a component part or the manufacturing equipment and processes by which it is made. With respect to an active bolster, when a change is made that affects the desired deployment trajectory (in terms of the shape, location, or timing of the expansion) then a significant redesign of the expansion pleats and/or other elements of the bolster have been necessitated even when the change in trajectory is small. Similarly, during testing verification of a design or of the tooling being used to manufacture the part, variations from the intended results may be identified which require changes to the tooling. Prior art designs and methods have required expensive and time consuming techniques for implementing the changes.